1. Field of the Invention
This invention relates generally to ink ribbons for impact printers, and particularly to a circular ink ribbon or ribbon disc with a central ink supply chamber for continuously resupplying the impact portion of the ribbon with ink by capillary action from the ink supply chamber to the film portion and by centrifugal forces acting on the ink as the ribbon disc is rotated during printing operations.
2. The Prior Art
Previous ink ribbons have generally been of two types, the first type being single use ribbons which contain only the ink trapped in the ribbon film during manufacture and which are intended to be discarded after a predetermined amount of use, and the second type being replenishable ink ribbons wherein the ribbon film is either continuously or intermittently recoated with ink prior to or during printing operations. Respective examples of these two types of disc ink ribbons are disclosed in U.S. Pat. No. 575,145 and U.S. Pat. No. 2,506,255. A shortcoming of the discardable ribbons is that print quality may be significantly degraded by the exhaustion of ink in the ribbon at a time well in advance of deterioration of the ribbon film. The normal procedure at this point is to discard the ribbon and replace it with a brand new ribbon. In an attempt to economize, devices have been known which include an ink storage receptacle and an ink applicator device to apply ink either continuously or intermittently to the ribbon film in an attempt to maintain a constant print quality. These devices have reached a high level of sophistication but have been confined primarily to the area of elongated web spooled ribbons. With this sophistication, however, there has arisen an equal increase in the complexity of the ribbon structure and in their cost and flexability in printer design is impeded by the required use of elongated web spooled ribbons.